9.6v too much for Shure ULX wireless?

[Schizoid75]

Last night I went from being very happy to very disappointed. Based on a post I read on TB a while back, I bought some Maha Energy PowerEx rechargeables. I opted for the 9.6v model assuming that they would provide a little longer life in my wireless which had been consuming my Energizer rechargeables about 1 per set. I put a fresh one in and the transmitter powers up and shows a full 3 bars of juice. Very happy. But when I play, nothing happens. Very disappointed. I duplicated my test this morning at home and sure enough, a standard new alkaline works just fine, but the 9.6v PowerEx's won't work in the unit. It powers up, it shows full juice, but something is preventing the audio from flowing.

So, I'm going to order one of the standard Maha 9v models and see how they do.

Anyone else have similar experiences with Maha batteries or Shure ULX wireless systems? I was thinking of upgrading to an X2, but the Shure is working fine, sounds okay, and a 4 new rechargeable 9 volts is still a couple hundred less than a new X2.

[Schizoid75]

In case anyone is curious, I ordered a couple of Maha Energy PowerEx 300mAh 9volts and it seems like they will work well with the Shure. The Energizer rechargeables I was using would maybe last 1 set. Even when taken right off the charger and put in my transmitter, they would usually show up with just one bar of juice left (out of three), two at the most. I just charged up the PowerEx and it had a full three bars and audio was working. Woo-hoo!

[Nic.]

I know I'm necro-ing an old thread but has anyone had any other observations on this? I'm about to order some 9.6v for my wireless, which is an XDS+, I know it's a different model and some people mentioned they didn't have problems with this, but just to be safe...

[Pilgrim]

Battery powered equipment typically does not respond well to over-voltage. I've used battery powered radio and TV gear for 30 years, and I've always had the best results using batteries of the specific voltage required by the device. I also am somewhat nervous about the potential for damaging a device if I subject it to over-voltage.

Wikipedia shows specs for voltage in 9V batteries, and it appears that 9.6V is a normal initial voltage for lithium polymer rechargeables and some NIMH batteries. However, this is .6V higher than the alkaline batteries for which the device was most likely designed. http://en.wikipedia.org/wiki/Nine-volt_battery

It does mention this: "The Lithium PP3 (U9VL-J, U9VL-X, U9VL-FP, U9VL-FP, Li9V & ER9V), is a consumer-replaceable, high energy density battery that can last up to 5 times longer than ordinary alkaline 9-volt batteries and up to 10 times longer than carbon-zinc batteries in many applications. An additional property of the lithium PP3 is its long shelf life, up to 10-years for the aluminum-jacketed U9VL-J battery."

Where you CAN cheat is on the amperage. A battery with more milliamp-hours (mAh) will last longer under use. Here's a reference chart that pre-dates the latest battery technologies:

http://www.techlib.com/reference/batteries.html

it also tells you how to calculate the length of the battery life based on how much current your device draws.

"To determine the battery life, divide the capacity by the actual load current to get the hours of life. A circuit that draws 10 ma powered by a 9 volt rectangular battery will operate about 50 hours: 500 mAh /10 mA = 50 hours."

There are also differences in the way voltage drops off under load, depending on whether you are using a rechargeable or alkaline battery. Ni-Cad batteries have some very bad habits in this respect - they can hit a "step" where the voltage drops suddenly to a lower level. The battery still can function, but this drop and fools the device into thinking the battery is discharged and it stops working. NIMH batteries normally don't have this problem.

On a practical basis, I stick with conventional alkaline 9V batteries because they're dependable, inexpensive and aren't terrible in landfills. I don't trust rechargeable batteries unless I take them right off the charger and drop them into the device. I've had too many problems with voltage based on the number of charge cycles, etc.